The Office of Global AIDS Coordinator (OGAC) Technical Guidance on Combination HIV Prevention defines a comprehensive HIV-prevention services program for MSM and their partners. The current proposal, Network-Based Recruitment of MSM into HCT, Care, Treatment and Prevention Services at Trusted Community-based Venues (TRUST) conducts an operations research prospective cohort study that evaluates an intervention that engages each element of the OGAC program in an integrated service model. The central hypothesis of TRUST is that Network-based recruitment to expand engagement of Nigerian MSM that links clients to combination prevention and comprehensive HIV and medical services delivered at community-trusted venues achieves measurable behavioral change, and durable high quality clinical outcomes. The three aims of TRUST are: 1) To evaluate Respondent Driven Sampling (RDS) as a recruitment tool, define barriers to HCT and service engagement and quantify acceptability of test and treat; 2) Measure the impact of the TRUST intervention on prevention outcomes; 3) Define the optimal service delivery model. To achieve these aims TRUST engages RDS, a mathematically defined peer-driven chain referral method to recruit 1200 clients from the MSM communities of Abuja and Lagos into a comprehensive service delivery at MSM community-based trusted venues. Barriers to HCT and treatment uptake are quantified. Validated behavioral and innovative ego network risk assessment tools previously developed by the investigative team in other low income settings are employed to measure patterns of behavior and sexual practice among MSM in Nigeria, and monitor impact of TRUST engagement on behavioral and biological (incident HIV and STI) outcomes. A particular focus is the role of network relationships in influencing behaviors and the potential of TRUST to understand and strengthen favorable peer-mediated behavioral norms. Given the propensity of structured HIV prevention interventions to lose effectiveness over time, the TRUST model, linking intensive combination prevention interventions to ongoing comprehensive clinical service delivery in MSM community owned venues is a platform that potentially reinforces sustained and lasting behavioral change that is mutually reinforced by members of cohesive sexual networks. Optimization of clinical service delivery is evaluated through objective clinical (e.g. treatment response, adherence), provider (clinical competence), site (impact of peer task shifting) and client (satisfaction) analyses. Th outputs of the TRUST initiative are: 1) expanded understanding of the extent of MSM social and sexual networks in Nigeria; 2) the drivers of risk practices and their modification; 3) the impact f HIV and STI treatment and combination prevention to reduce high risk behaviors and sexual practices; 4) an objective assessment of the quality of HIV and medical services delivered in a nontraditional venue. Together this information will guide institution of best practices for scale p of TRUST as a PEPFAR model of service delivery with the potential for high impact.